1. Field of the Invention
The present invention relates to an endoscope insertion section configured to be inserted into a lumen, an endoscope including this endoscope insertion section, and an attachment unit attached to this endoscope insertion section.
2. Description of the Related Art
US 2010/0076264 discloses an endoscope including an insertion section which is configured to be inserted into a lumen, and an attachment unit which is rotatable about a longitudinal axis with respect to the insertion section. The attachment unit includes a tube main body, and a fin portion spirally provided on an outer peripheral portion of the tube main body along the longitudinal axis. Further, a ring-like rotor is disposed on an outer peripheral portion of the insertion section to be rotatable about the longitudinal axis with respect to the insertion section. The attachment unit is disposed on the rotator in a fixed state. Therefore, when the rotor rotates, the attachment unit and the rotor integrally rotate about the longitudinal axis with respect to the insertion section. Furthermore, at a position where the rotor is not placed in directions parallel to the longitudinal axis, a gap is provided between the attachment unit and the outer peripheral portion of the insertion section, whereby rotation properties of the attachment unit with respect to the insertion section is improved. Therefore, at each of a distal end and a proximal end of the attachment unit, the gap is provided between the attachment unit and the outer peripheral portion of the insertion section.
When such a configuration, when the insertion section of the endoscope is inserted into a lumen, for example, the inside of a small intestine or the inside of a large intestine, the fin portion of the attachment unit comes into contact with a paries. In this state, when the rotor and the attachment unit are rotated with respect to the insertion section, propulsive force in the directions parallel to the longitudinal axis acts on the insertion section. With the propulsive force, insertability of the insertion section of the endoscope in the lumen is improved.
Further, Jpn. PAT. Appln. KOKAI Publication No. 2005-31912 discloses an endoscope in which the rotary gear rotates about a gear axis and an attachment unit can thereby rotate about a longitudinal axis. In this endoscope, a gear portion, which meshes with the rotary gear, is provided on an inner peripheral portion of an attachment unit.